Surface light source apparatus with dual-side emitting light

ABSTRACT

A surface light source apparatus with dual-side emitting light includes at least a cathode wire structure, a transparent anode structure, a fluorescent layer and a low-pressure gas layer. The transparent anode structure is a surface structure, wherein the cathode wire structure and the transparent anode structure are parallel to each other. The fluorescent layer is located between the cathode wire structure and the transparent anode structure. The low-pressure gas layer fills the space between the cathode wire structure and the transparent anode structure and functions to induce the cathode evenly emitting electrons. The electron mean free path of the low-pressure gas layer allows at least a sufficient number of electrons to directly impact the fluorescent layer under an operation voltage.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims the priority benefit ofU.S. application Ser. No. 12/050,186, filed on Mar. 18, 2008, whichclaims the priority benefit of Taiwan application serial no. 96151533,filed on Dec. 31, 2007. The entirety of each of the above-mentionedpatent applications is hereby incorporated by reference herein and madea part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a light source apparatus, andmore particularly, to a surface light source apparatus with dual-sideemitting light to produce desired light.

2. Description of Related Art

A light source apparatus is widely used in our daily life. A traditionallight source apparatus, for example, a bulb, produces visual lightthrough the filament thereof with a high temperature after turning on.The bulb light source is counted as spot-like light source. After thespot-like light source, a tube-like light source was developed as well.Thereafter, through long time developments and modifications, a surfacelight source apparatus was lunched, which now is broadly used in, forexample, flat displays.

A surface light source works based on various mechanisms. FIG. 1 is across-sectional diagram showing a mechanism of a conventional surfacelight source apparatus. Referring to FIG. 1, the light-emitting isproduced by such a mechanism: connecting a power supply 106 to twoelectrode structures 100 and 102; producing an electric field under anoperation voltage by the electrode structures 100 and 102 so as toestablish gas discharge, termed as plasma discharge as well; ionizingthe gas 104 so that the electrons 110 in the conductive gas likely hitthe gas molecules to cause an electron transition with the ultravioletemission; impacting the fluorescent layers 108 a, 108 b and 108 ccorresponding to different colors on the electrode structure 102 by theemitted ultraviolet (UV); finally emitting visual light 112 after thefluorescent layers 108 a, 108 b and 108 c (for example, a redfluorescent layer, a green fluorescent layer and a blue fluorescentlayer) absorb the UV. The electrode structure 100 herein is alight-emitting surface; therefore, the electrode structure 100 usuallyis a transparent material, for example, one composed of glass substrateand an ITO (indium tin oxide) transparent conductive layer.

FIG. 2 is a cross-sectional diagram showing another mechanism of aconventional surface light source apparatus. Referring to FIG. 2, acathode structure layer 122 is disposed on a glass substrate 120, aplurality of conical conductors 124 are disposed on the cathodestructure layer 122, a gate layer 126 is disposed on the conicalconductors 124 and a plurality of holes are made on the gate layer 126and the holes are corresponding to the conical conductors 124. An anodestructure layer 128 with a transparent anode layer is disposed onanother glass substrate. In addition, a fluorescent layer 130 isdisposed on the anode structure layer 128, and a high electric fieldbetween the cathode and the anode makes electrons 132 escaped from thetips of the conical conductors 124. Thereafter, the electrons 132 areaccelerated by the electric field and then impact the fluorescent layer130 so as to make the fluorescent layer 130 emits light.

The above-mentioned two conventional light-emitting mechanismsrespectively have advantages and disadvantages of their own. Themechanism based on gas discharge has advantages of structure simplicityand easily light-emitting, but to emit light, it needs to produce plasmafirst and the light-emitting mechanism is based on secondary energyconversion, which consumes a lot of electrical power. In contrast, themechanism based on field emission, the corresponding light source iscounted as a cold light source similar to a cathode ray tube (CRT),where electrons in high speed within vacuum directly impact fluorescencepowder to emit visual light. The second mechanism is advantageous inhigh luminance, electricity-saving and easiness to form a surface lightsource structure, but disadvantageous in that the process needs to makean even emission material grow on a cathode or to spread the saidmaterial on the cathode, and to implement the process the secondmechanism requires a needle-like structure or a carbon nanotube, so thata microstructure with a large aspect ratio (ratio of depth over width)enables the electrons to overcome the work function of the cathode toget rid of the cathode and then travel into a vacuum space. Therefore,the second mechanism is hard to evenly form a cathode structure withlarge area. In addition, for the second mechanism, the distance betweenthe cathode and the anode for establishing field emission must beaccurately controlled, which accordingly requires a strict specificationon a spacer structure; plus, the vacuum packaging with the secondmechanism is often a worried problem.

Note that the above-mentioned light source apparatuses are targeting thearchitecture for mono-direction light-emitting. However, such amono-direction light-emitting apparatus nevertheless has applicationlimitation.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a surface light sourceapparatus with dual-side emitting light served as a lamp source modulefor lighting or a display apparatus.

According to an embodiment, the present invention provides anothersurface light source apparatus with dual-side emitting light, whichincludes at least a cathode wire structure, a transparent anodestructure, a fluorescent layer and a low-pressure gas layer. Thetransparent anode structure is a surface structure, wherein the cathodewire structure and the transparent anode structure are parallel to eachother. The fluorescent layer is located between the cathode wirestructure and the transparent anode structure. The low-pressure gaslayer fills the space between the cathode wire structure and thetransparent anode structure and functions to induce the cathode evenlyemitting electrons. The electron mean free path of the low-pressure gaslayer allows at least a sufficient number of electrons to directlyimpact the fluorescent layer under an operation voltage.

According to an embodiment, the present invention provides yet anothersurface light source apparatus with dual-side emitting light, whichincludes a first conductive transparent substrate and a secondconductive transparent substrate opposite to each other, and the twoconductive transparent substrates are respectively served as an anodestructure. A fluorescent structure layer is located on the firstconductive transparent substrate and the second conductive transparentsubstrate. A spacer is located between the first conductive transparentsubstrate and the second conductive transparent substrate to construct aspace. A low-pressure gas layer fills the space and functions to inducethe cathode evenly emitting electrons. A filamentary cathode structureis distributed on a plane between the first conductive transparentsubstrate and the second conductive transparent substrate. The electronmean free path of the low-pressure gas layer allows at least asufficient number of electrons for transverse moving and to directlyimpact the fluorescent layer under an operation voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a cross-sectional diagram showing a mechanism of aconventional surface light source apparatus.

FIG. 2 is a cross-sectional diagram showing another mechanism of aconventional surface light source apparatus.

FIG. 3 is a cross-sectional diagram of a surface light source apparatuswith dual-side emitting light according to an embodiment of the presentinvention.

FIG. 4 is a cross-sectional diagram of a surface light source apparatuswith dual-side emitting light according to another embodiment of thepresent invention.

FIGS. 5-7 are cross-sectional diagrams of surface light sourceapparatuses with dual-side emitting light according to other embodimentsof the present invention.

FIGS. 8-11 are cross-sectional diagrams of surface light sourceapparatuses with dual-side emitting light according to yet anotherembodiment of the present invention.

FIGS. 12A and 12B are a side view diagram and a top view diagram of asurface light source apparatus with dual-side emitting light accordingto yet another embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

The present invention provides a surface light source apparatus withdual-side emitting light, which is able to achieve light-emitting effectby controlling the vacuum level of the gas based on the electronemission mechanism. In addition, in association with properly disposingtransparent electrodes and transparent substrates, the present inventionachieves dual-side emitting light. The mechanism the present inventionadopts makes the process of fabricating a surface light source apparatuswith dual-side evenly emitting light simpler. Moreover, by properlyselecting fluorescent materials, the present invention can produce asurface UV light source or a light source with other wavelengths such asvisual light or infrared light as well. In addition to the applicationsof lighting and decoration, the surface light source apparatus withdual-side emitting light of the present invention can be served as alight source for a display. The material of the transparent substratecan be a hard material or a flexible material. The surface light sourceapparatus can be planar one or curve one depending on a real need. Inthe following, several embodiments, but not limited by the presentinvention, are explained. In a real application, the depictedembodiments in follows can be combined for use or individually used.

The light source apparatus provided by the present invention takesadvantage of gas conductive characteristic to educe sufficient electronsout of the cathode. While the electrons are travelling in the thin gas,due to a longer electron mean free path of the thin gas, there are stillsufficient electrons in the travel end to directly impact, for example,the fluorescence powder on the anode to excite the fluorescence powderfor emitting light, wherein the fluorescence powder is able to beexcited to emit light. If UV is needed, the element proportion of thefluorescence powder can be adjusted to emit UV light, for example, thelight in wavelength of 100 nm-400 nm. In addition, the luminousintensity can be controlled by adjusting the voltage.

FIG. 3 is a cross-sectional diagram of a surface light source apparatuswith dual-side emitting light according to an embodiment of the presentinvention. Referring to FIG. 3, the present invention requires a spaceto accommodate low-pressure gas. The space for the low-pressure gas isformed by two transparent substrates 200 and 202 and spacers 204,wherein the low-pressure gas layer can be implemented by a generaltechnique so as to be omitted for depiction.

A transparent cathode structure 206 of the present invention is disposedon the transparent substrate 200 and a transparent anode structure 208is disposed on the transparent substrate 202. The spacers 204 aredisposed between the transparent substrates 200 and 202 to form a spaceto accommodate a low-pressure gas layer. The space herein can be dividedinto a plurality of smaller spaces or a single one without dividing,which depends on an application need without specific limitation. Thetransparent material is, for example, indium tin oxide (ITO), indiumzinc oxide (IZO) or other common materials of transparent conductiveoxides.

The transparent cathode structure 206 and the transparent anodestructure 208 are, for example, opposite to each other and respectivelya surface structure. In general, a fluorescent layer 210 is locatedbetween the transparent cathode structure 206 and the transparent anodestructure 208, and preferably disposed on the transparent anodestructure 208. The low-pressure gas layer fills the space between thetransparent cathode structure 206 and the transparent anode structure208 for inducting the cathode to evenly emit electrons. The electronmean free path of the low-pressure gas layer allows at least sufficientelectrons to directly impact the fluorescent layer under an operationvoltage. The pressure of the low-pressure gas layer ranges between10-10⁻³ torr, and the gas in the low-pressure gas layer includes, forexample, for example, inert gases, atmosphere, He, Ne, Ar, Kr, Xe, H₂ orCO₂. The optimized pressure is depends on the gas and the distancebetween cathode and anode.

The educed electrons 212 in the low-pressure gas layer are acceleratedto move towards the transparent anode structure 208. Due to a longerelectron mean free path of the thin gas, there are still sufficientelectrons 212 in the travel end to directly impact the fluorescent layer210. On the other hand, the ionized positive gas ions 214 in thelow-pressure gas layer would travel towards the transparent cathodestructure 206 and impact the cathode, which also contributes forproducing and increasing the secondary electrons 216. The way toeffectively produce secondary electrons is depicted in later. Usually,different pressure requires a different operation voltage, wherein theluminance is increased with an increasing operation voltage and they aresubject to a linear relationship.

The transparency property of the transparent substrates 200 and 202enables the light 218 and 220 produced by the fluorescent layer 210 totravel through the transparent substrates 200 and 202 to achieve theeffect of dual-side light-emitting.

The fluorescent layer 210 can be a mono-layer structure. However, thefluorescent layer 210 can also be, for example, an overlapped layerstructure or a mixed layers structure, depending on the differentfluorescent layer. Both the overlapped layer structure and the mixedlayer structure are made of different fluorescent materials, wherein theoverlapped layer structure is composed of, for example, a plurality oflayers of different fluorescent layer materials to produce blendedlight, for example, white light blended bye and they are subject redlight, green light and blue light. The mixed layers structure is aplurality of fluorescent layers in different colors are disposed atdifferent regions to respectively produce light corresponding to adefined frequency to achieve a light-blending effect. In addition,except for the visual light materials, the fluorescent layer can useinfrared material or UV material.

The above-mentioned surface light source apparatus with dual-sideemitting light is a basic structure only. In order to promote theluminous efficiency, an additional auxiliary function layer is disposedon the transparent cathode structure 206 or the transparent anodestructure 208. FIG. 4 is a cross-sectional diagram of a surface lightsource apparatus with dual-side emitting light according to anotherembodiment of the present invention. Referring to FIG. 4, to moreeffectively produce secondary electrons 216 to increase the luminance, asecondary electron material layer 222 is disposed, for example, on thetransparent cathode structure 206, wherein the material of the secondaryelectron material layer 222 includes, for example, magnesium oxide(MgO), terbium oxide (Tb₂O₃), lanthanum oxide (La₂O₃) or cerium oxide(CeO₂).

FIGS. 5-7 are cross-sectional diagrams of surface light sourceapparatuses with dual-side emitting light according to other embodimentsof the present invention. Referring to FIG. 5, an emitter material layer224 can be further disposed on the transparent cathode structure 206 toprovide a surface structure for making discharge easier and lowering theoperation voltage. The emitter material layer 224 is made of, forexample, includes metal material, carbon nanotubes, carbon nanowalls,carbon nanoporous material, cylinder-like ZnO or ZnO.

In the embodiment of FIG. 5, the emitter material layer 224 is disposed,for example but not limited to, on the transparent cathode structure206. Referring to FIG. 6, another emitter material layer 226 is disposedon the transparent anode structure 208 for facilitating discharge aswell. Referring to FIG. 7, two emitter material layers 224 and 226 aredisposed respectively on the transparent cathode structure 206 and thetransparent anode structure 208.

Although in FIGS. 5-7 the structure has an emitter material layer, butif needed, a secondary electron material layer can be additionallydisposed as shown by FIG. 4. In fact, the embodiments of the presentinvention can be implemented in various ways or in a combination formthereof, which the present invention does lot limit.

FIG. 8 is a cross-sectional diagram of surface light source apparatuseswith dual-side emitting light according to yet another embodiments ofthe present invention. Referring to FIG. 8, in the embodiment, anadditional transparent conductive protection layer 228 is disposed onthe fluorescent layer 210, wherein the transparent conductive protectionlayer 228 is conductive for protecting the fluorescent layer 210; inmore detail, the transparent conductive protection layer 228 preventsthe fluorescent layer 210 from being impacted by ions and avoids thefluorescence body from burning and damage so as to extend the lifetimeof the fluorescent layer 210. Since the transparent conductiveprotection layer 228 is for protecting, only one thin layer having, forexample, a couple of nanometres is enough to form the transparentconductive protection layer 228. Besides, the emitter material layer 224can be disposed, for example, on the transparent cathode structure 206.

The fluorescent layer in the above-mentioned embodiment is designed as asurface structure, but it can be modified as well. FIG. 9 is across-sectional diagram of surface light source apparatuses withdual-side emitting light according to yet another embodiments of thepresent invention. Referring to FIG. 9, two transparent substrates 290and 298 and spacers 296 are disposed similarly to the foregoingdepiction so as to construct a space to accommodate low-pressure gas.Bit the present embodiment is unique in the arrangement of theelectrodes and fluorescent layer. A cathode structure 292 and an anodestructure 294 are disposed on a same substrate 290. Since the cathodestructure 292 and the anode structure 294 occupy smaller areas,therefore, they are made of transparent conductive material ornon-transparent conductive material, and preferably transparentconductive material. A fluorescent structure layer is disposed on thetransparent substrate 290 and located between the cathode structure 292and the anode structure 294.

A fluorescent layer includes, for example, a plurality of fluorescencemono-bodies, wherein the surface of each fluorescence mono-body has afluorescent material layer. The fluorescence mono-body 295 is, forexample, a sphere-like fluorescence mono-body and the surface of eachfluorescence mono-body 295 has a fluorescent material layer; thefluorescence mono-body 295 can be a cylinder-like fluorescence mono-bodyand the surface thereof has a fluorescent material layer as well. In theembodiment, electrons move in a direction as shown by an arrow and theelectrons are transverse moving. Since both the transparent substrates290 and 298 are transparent, the produced light is emitted from the twosides.

FIG. 10 is a cross-sectional diagram of surface light source apparatuseswith dual-side emitting light according to yet another embodiments ofthe present invention. Referring to FIG. 10, in a surface light sourceapparatus with dual-side emitting light, the spacers 232 are allowed tobe disposed between the electrodes 206 and the fluorescent layer 210 toconstruct a space for accommodating the low-pressure gas, where thespacers 232 between the substrates are not in charge of supporting thesubstrates, which reflects a modification of the above-mentionedembodiment for partitioning the space.

Similarly to FIG. 3, the electrode structure can be modified as well.FIG. 11 is a cross-sectional diagram of surface light source apparatuseswith dual-side emitting light according to yet another embodiments ofthe present invention. Referring to FIG. 11, two transparent substrates300 and 302 and spacers 304 construct a space for accommodatinglow-pressure gas as described before. In the embodiment, at least acathode wire structure 310 is disposed in the space over the transparentsubstrate 300. In the embodiment, the cathode wire structure 310 is, forexample, a plurality of ones. A transparent anode structure 306 is asurface structure, formed on the transparent substrate 300 and parallelto the transparent anode structure 306. A fluorescent layer 308 islocated between the cathode wire structures 310 and the transparentanode structure 306, while the fluorescent layer 308 is directly formedon, for example, the cathode wire structures 310.

Since the cathode wire structure 310 is, for example, a filamentarystructure, thus, does not affect the light-emitting quality.

In the same way, the present invention can have other modifications.FIGS. 12A and 12B are a side view diagram and a top view diagram of asurface light source apparatus with dual-side emitting light accordingto yet another embodiment of the present invention. Referring to FIG.12A, two conductive transparent substrates 400 and spacers 406 constructa space for accommodating low-pressure gas as described before, whereinthe conductive transparent substrate 400 is, for example, conductiveglass served as an anode. A fluorescent layer 402 is disposed on the twoconductive transparent substrates 400. At least a cathode wire structure404 is disposed in the space between the two conductive transparentsubstrates 400. In the embodiment, the cathode wire structure 404 is,for example, a plurality of ones. The cathode wire structures 404 aredistributed as shown by FIG. 12B, on a plane between the two conductivetransparent substrates. Since the cathode wire structure 404 is, forexample, a surface structure, thus, the cathode wire structure 404 canbe served as a dual-side emitting light substrate.

The surface light source apparatus with dual-side emitting lightprovided by the present invention can be further applied to dual-sideimage displaying or curve surface image displaying.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A surface light source apparatus with dual-side emitting light,comprising: at least a cathode wire structure; a transparent anodestructure, characterizing a surface structure, wherein the cathode wirestructure and the transparent anode structure are parallel to eachother; a fluorescent layer, located between the cathode wire structureand the transparent anode structure; and a low-pressure gas layer,filling a space between the cathode wire structure and the transparentanode structure and functioning to induce cathode for evenly emittingelectrons, wherein an electron mean free path of the low-pressure gaslayer allows at least sufficient electrons to directly impact thefluorescent layer under an operation voltage.
 2. The surface lightsource apparatus with dual-side emitting light according to claim 1,further comprising a first transparent substrate, a second transparentsubstrate and a spacer, wherein the spacer is located between the firsttransparent substrate and the second transparent substrate to constructa space for accommodating the low-pressure gas layer, wherein thecathode wire structure is located in the space over the firsttransparent substrate, and the transparent anode structure and thefluorescent layer are formed on the first transparent substrate.
 3. Thesurface light source apparatus with dual-side emitting light accordingto claim 1, further comprising an emitter material layer disposed on thetransparent anode structure.
 4. The surface light source apparatus withdual-side emitting light according to claim 3, wherein the emittermaterial layer comprises a surface structure to facilitate discharging.5. The surface light source apparatus with dual-side emitting lightaccording to claim 1, further comprising a transparent conductiveprotection layer disposed on the fluorescent layer for protecting thefluorescent layer.
 6. The surface light source apparatus with dual-sideemitting light according to claim 1, wherein the pressure of thelow-pressure gas layer ranges between 10-10⁻³ torr.
 7. The surface lightsource apparatus with dual-side emitting light according to claim 1,wherein the fluorescent layer comprises a mono-layer structure.
 8. Thesurface light source apparatus with dual-side emitting light accordingto claim 1, wherein the fluorescent layer comprises an overlapped layersstructure or an auxiliary structure respectively containing variousdifferent fluorescence materials.
 9. The surface light source apparatuswith dual-side emitting light according to claim 1, wherein thefluorescent layer has a plurality of regions for respectively producinglight with a corresponding frequency.
 10. A surface light sourceapparatus with dual-side emitting light, comprising: a first conductivetransparent substrate and a second conductive transparent substrate,opposite to each other and served as an anode structure; a fluorescentstructure layer, disposed on the first conductive transparent substrateand the second conductive transparent substrate; a spacer, disposedbetween the first conductive transparent substrate and the secondconductive transparent substrate to construct a space; a low-pressuregas layer, filling a space and functioning to induce cathode for evenlyemitting electrons; and a filamentary cathode structure, distributed ona plane between the first conductive transparent substrate and thesecond conductive transparent substrate, wherein an electron mean freepath of the low-pressure gas layer allows at least sufficient electronsto transversely move and directly impact the fluorescent structure layerunder an operation voltage.
 11. The surface light source apparatus withdual-side emitting light according to claim 10, wherein the pressure ofthe low-pressure gas layer ranges between 10-10⁻³ torr.